PORE WATER CONTRIBUTION TO IN-SITU SAMPLING OF POLYCYCLIC AROMATIC HYDROCARBONS IN SEDIMENT USING LOW DENSITY POLYETHYLENE

Resumen

Passive sampling with low-density polyethylene (LDPE) was assessed to study the way it accumulates contaminants in sediment. Strips of LDPE were deployed in river sediment for a period of two months to evaluate their polycyclic aromatic hydrocarbon (PAH) accumulation following two modes: LDPE buried in sediment and exposed to pore water flow and contaminants desorbed from particles were compared to LDPE strips in the same sediment but in a confined space. The results present an obvious difference of accumulation between the two modes of exposure. LDPE exposed to pore water accumulated PAH depending on their hydrophobicity whereas LDPE only exposed to contaminant desorption from confined particles did not accumulate nor desorb PAH significantly. This observation shows that LDPE only takes up PAH present in pore water and not the PAH bound to sediment particles. Accumulation in LDPE is not the result of forced desorption from particles. The present study also found that LDPE sampling cannot estimate adsorbed molecules in confined sediment nor in turbid water. LDPE is an efficient tool for investigating pore water, the fate of micropollutants in sediment, the effect of bioturbation and bioirrigation on micropollutants and the effect of micropollutants on bioturbation activity.